The purpose of this project is to continue studies which are allowing us to obtain a better understanding of the effects of hypertension on WAIS and neuropsychological test measures with advancing age. Continuation of our ongoing longitudinal studies will allow us to: 1) follow subjects, already tested three times, for an additional five years (Time 4 testing); 2) perform Time 3 testing and complete Time 2 testing for subjects tested initially during the 1981-1984 grant period; 3) perform Time 2 testing for subjects tested initially during the current grant period (1985- 1989); 4) expand the number of subjects in our overall cross- sectional design so that we obtain the statistical power necessary for examinations of the influence of plasma renin activity, antihypertensive medications, age at initial testing, subtypes of hypertension (e.g., complications, secondary, orthostatic, isolated systolic), and blood pressure levels, on performance. Continued collection of cross-sectional data will also allow further tests of blood pressure by age interactions for even older groups of hypertensives and normotensives. One universal failing of most studies in this area is inadequate numbers of subjects, a failure that can only be remedied by persistent and continuous collection of data under controlled conditions. Although the examination of age changes and age differences in performance for uncomplicated essential hypertensives continues to be of major importance, an increased emphasis is also being placed upon types of hypertension which involve higher risk of morbidity and mortality. Questions regarding the clinical significance of findings as well as statistical significance are raised.